The invention pertains to a device for cleaning, in particular for dry ice cleaning, the inner walls of vulcanization molds for tires, said molds being divided for opening into upper and lower partial molds, said cleaning being by means of a blasting material, with a movably provided blasting material device/nozzle, moved along at least four axes by means of a manipulation device, for application of blasting material to the inner walls, and with a device designed as an isolation hood for encapsulation of the blasting material application device and of the thereby cleaned inner walls with respect to the environment, where the isolation hood can be tightly joined at the outer perimeter to a partial mold and has openings and leads for supply elements for power, compressed air and blasting material.
For cleaning the inner surface or the inner walls, respectively, of molds and tools used in industry, essentially meaning those made of metal, different types of chemical and physical cleaning methods and means are known.
Whereas the chemical cleaning method places strict demandsxe2x80x94specified by legal statutesxe2x80x94on the safety and disposal equipment due to the aggressive media often used, with regard to physical cleaning methods in which the impurities, as a rule, are removed from the surface to be cleaned by sandblasting or by directing blasting material composed of sand, metal or glass particles thereon, it is necessary that the cleaning itself be carried out in special cabinets, so that the component to be cleaned first has to be removed from the corresponding machine and has to be placed into such cabinet.
An additional alternative consists in that the components can be cleaned by exposure to high-velocity dry ice pellets, that is, small, dry ice particles about the size of a grain of rice. With dry ice we are delaying with carbon dioxide cooled to at least xe2x88x9278.5xc2x0 C. and converted into the solid state, which has the advantage that under atmospheric pressure it passes directly from the solid phase into the gas phase, with no melt liquid being produced. Thus, in a particularly simple manner, namely with normal compressed air, both the exposure to high-velocity dry ice and also the removal and disposal of dirt particles takes place.
When using high-speed dry ice pellets, several favorable effects will occur. In addition to the initially occurring mechanical removal of dirt and impurities by means of abrasion, a powerful, point-wise cooling of the exposed region will occur, so that the impurities, and in particular the rubber residues in tire molds, will become embrittled and are easier to remove. In addition, upon impact of the dry ice pellet against the surface under atmospheric pressure, the already mentioned transition of the dry ice to the gaseous state occurs, so that a roughly 700-fold increase in volume of the dry ice will occur. The gas cloud produced in this manner is able to blow out the subcooled and embrittled impurities, without itself damaging the substrate or the surface itself.
However, with dry ice cleaning exceptionally large sound emissions occur, and it is therefore necessary to supply and then subsequently to eliminate a large quantity of compressed air mixed with dry ice, carbon dioxide or dirt. In this case as well, it is necessary either to treat the component being cleaned in special cabinets, or in the event that the component is to be cleaned in situ, to shield the environment in a very cost-intensive manner against the emissions of the dry ice cleaning method.
In addition, many cleaning methods, in particular the cleaning of vulcanization molds for tires, have to proceed rather quickly so that production stoppages will be avoided. In addition, vulcanization molds for tires are very hot, even for some time after removal of the vulcanization material, so that removal of the molds and their transport into a separate cabinet can occur only after cooling, and this takes a considerable amount of time. Thus, cleaning is very difficult and sometimes cannot even be carried out by manually operated blasting material systems within the vulcanization press (in situ) due to the aforementioned emissions and the heat.
DE 197 12 513 A1 discloses a method and a device for cleaning an inner wall of a mold by means of dry ice, where the cleaning can take place within the vulcanization press, without the vulcanization mold having to be dismantled.
The vulcanization molds for tires, as a rule, are designed as partial molds which can be opened after the vulcanization process. In this case, on the one hand there segmented molds, which usually have an upper mold which surrounds the vulcanized tire on one side and on the road strip or tread, and which feature laterally adjustable segments, in the tread region for closing the mold, and which comprise a lower mold (side dish) with which the mold is closed and the remaining tire side is shaped and vulcanized.
On the other hand, there are two-partial molds which are nearly identically designed without displaceable segments, and each forms one side wall and covers roughly half of the tread region.
With regard to the device disclosed in DE 197 12 513 A1, encapsulation of the region being cleaned is used, which takes place by means of the two partial molds and of a possibly telescoping or bellows-like mantle, so that the mantle or the encapsulation also contains the blasting material device.
The disadvantage of this kind of encapsulation consists in that a complete encapsulation can only take place when the mantle is stretched between two partial molds and is fixed to them and held in place, so that the movement of the encapsulation up to the still hot molds requires a considerable amount of manual effort and also can only be carried out after a longer cool-down time. In this case, the encapsulation or the mantle must be flexible enough so that different positions of the two partial molds relative to each other can be handled, and yet still a movable lateral opening for a robot arm is provided, which causes the overall structure to be very complex.
The heat radiation, with the heating of robot devices/controls to over 60xc2x0, makes the use of industrial robots problematic, and in addition, requires a spatial repositioning or new reading of the precise robot standpoint based on three reference points before each cleaning a mold, which requires a reprogramming before each new cleaning process, unless stationary or at least rail-based robot devices are used, but these, in turn, disrupt the normal production sequence.
Document DE 195 35 557 A1 discloses a device for cleaning an inner wall of a mold with dry ice pellets, with a cover hood matching the opening cross section of the mold, through which at least the supply lines extend, and which has in its edge region at least one elastic seal for placement against the mold. However, the disadvantage of this device is not only that all handling devices for adjusting the jet nozzle, but also for adjusting the cover hood are placed at a central carrier passing through the cover hood, with parts of the central carrier and several actuating devices, especially those for height adjustment of the nozzle, being located outside and beneath the cover hood. Thus, the design height of the entire device has to be increased to such an extent that in-situ cleaning, at least of tire molds for smaller tires, is not possible. In addition, a number of rotary transmission lead throughs equipped with bearings are required in the cover hood, so that the weight of the device is increased and its handling is made more difficult.
Thus one problem for the invention was to design a device for cleaning the inner walls of molds by means of blasting material, in particular for dry ice cleaning of the inner regions of vulcanization molds, which can be employed in situxe2x80x94i.e.,in the vulcanization press after opening the molds and without waiting out the cooling time, which allows a dependable and complete encapsulation of the high-speed material or cleaning regions, which can be installed in a simple manner without manual activity and with which any kind of partial molds of vulcanization molds of very different dimensions and press types, for example, within hoist and pivoted presses, can be cleaned regardless of their positions relative to each other.
This problem is solved by the properties of the main claim. Additional favorable embodiments are presented in the subclaims.
In this case, the isolation hood is suspended from an extender arm of a transport device moving essentially transverse to its axis and extending essentially horizontally, and it is equipped with a replaceable adapter ring located in the region of its opening for making a tight connection with the outer perimeter of a partial mold, so that the blasting material device and the manipulation device are held in and are fully encapsulated within the blasting material space or cleaning space formed by the partial mold, adapter ring and isolation hood.
Due to this kind of design, in which the opening the isolation hood is pressed only against one partial mold or against its outer perimeter to form a seal by means of an adapter ring, a thorough automation of the cleaning process can be achieved without additional manual activity, where moreover, the region to be encapsulated is minimized and is limited essentially to the dimensions of the opened press. With this kind of design, in which the insulating hood is suspended from a moving extender arm of a transport device extending essentially transverse to its axis, it is possible, immediately after opening the vulcanization press and removing the tire, to attach first the isolation hood and the cleaning devices present in it, e.g., to the upper partial mold, then to clean it, thereafter to interrupt the cleaning process and in the same manner, after replacement of the adapter ring, to set the isolation hood on the lower partial mold by simple turning and repositioning, whereupon it can also be cleaned. Now in this case, because of the moving extender arm, which can be locked in any position, it makes no difference whether the vulcanization press is a hoist press, which vertically separates the upper or lower mold in one axis, or whether it is a pivoted press in which, for example, the upper mold is hinged to pivot upward.
By means of the replaceable adapter ring located in the region of its opening, the isolation hood is suitable for making a sealed connection to the outer perimeter of any particular partial mold. By means of these adapter rings, the isolation hood, or its connection opening, can be adapted to any particular mold dimensions and shaped, for example, to the connection dimension or to the outer perimeter of segmented molds, or of two-partial molds of differing dimensions and different surface shapes at their edge regions. In this case, the adapter ring can have, for example, a perimeter gasket in the region of its connection to the partial mold, and said gasket can be pressed against the partial mold, or it can even be designed so that its connection region is complementary to the surface shape of the partial mold.
Preferably, the isolation hood has a lead for a vacuum line for dirt particles and/or blasting material that accumulates during cleaning. In the case of dry ice cleaning, this suction is reduced to the suction of compressed air, or to a single exhaust line, since due to the sealed connection of the isolation hood to only one partial mold at a time, a small pressure space is produced from which the gaseous carbon dioxide introduced by compressed air in the form of dry ice pellets, plus the dirt, can be removed.
In one simple design, this kind of exhaust line can be designed as a tubular channel equipped with a gas-permeable filter, for example, in the base region of the isolation hood, so that the inner pressure in the blasting material or cleaning space, and thus the pressure force needed to press the adapter ring against the mold, is reduced.
Preferably, the blasting material device/nozzle provided on the manipulator device can move in four axes, and
a) the manipulation device is designed to rotate within the isolation hood and around the vertical axis of the isolation hood or an axis parallel to this axis, and
b) has a support arm extending into the vicinity of the inner wall of the isolation hood, there being on said arm a carriage designed to move essentially horizontally, i.e., across the isolation hood, and where
c) the skid has a lifting bar moving essentially vertically, i.e., parallel to the vertical axis of the isolation hood, where
d) the lifting bar has at its upper end, i.e., at the end facing the partial mold to be cleaned, a pivoted device holding the blasting material device/nozzle, with its pivot axis aligned essentially at right angles to the vertical axis of the isolation hood and at right angles to the vertical movement of the skid.
Due to this particular design of the device, it is possible to clean accurately a large number of mold designs (upper mold and lower mold) and mold dimensions, even when the isolation hood is connected via the different adapter devices or adapter rings to molds whose outer perimeter does not correspond to the perimeter of the isolation hood. The outlet cross section of the nozzle, in every case, can be placed in such proximity to the inner surface of the mold and then controlled so that optimum application distances of the blasting material, or optimum application angles of the blasting material can be achieved, and successive surface regions can be cleaned according to a previously defined grid.
Preferably, the isolation hood located above an extender oh the transport device is designed as moving in five axes, wherein
d) the extender arm can move or telescope in the direction of its axis and in essentially horizontal translation, and also
e) it is designed to move perpendicular to its axis and can move in essentially vertical translation and can rotate about its axis, wherein
f) the isolation hood is cardan suspended at the end of the extender arm.
Due to the suspension of the isolation hood from an extender arm designed in this manner, the isolation hood with the adapter ring can be very easily attached to partial molds of different press types, for example, equally to molds that are pressed apart in only the vertical direction, and to molds in hinged pivoted presses, which can assume any particular slanting spatial position in the opened state.
Now just as is the case for the movements in four axes of the manipulation or blasting material device, all movements in the five axes are controlled and. definable, so that, for example, by simple means adjustment of the level between the transport device and partial mold or press is possible; also adjustment of the angular position of the isolation hood plus adapter device is possible for a tipped/pivoted upper mold (partial mold), and rotation for connection to the lower mold (partial mold) is also possible. In addition, it is desirable to design one or more of the bearings as resilient bearings to compensate for position differences in the connecting or docking process to the partial molds, for example, as resilient sliding bearings with leaf springs.
To improve the sound isolation, the isolation hood is designed as a special sound suppression hood, where essentially its walls are equipped with sound-absorbent materials. This can be done such that the isolation hood is of double-wall design and the space between the walls is filled with sound-absorbing material, such as special foam, or it can be done such that rubberized sound-absorbent mats are placed on the inside of the isolation hood. Of course, it is also possible to design the isolation hood itself to be of sound-absorbent material, which as already mentioned above, can additionally be at least partially gas-permeable and can have filter properties.
One particularly favorable design of this kind of sound-absorbent hood consists in that the isolation hood is designed as a polygon, preferably as a rectangle, where the adapter ring then represents the transition from the polygonal shape of the isolation hood to the adjoining shape of the vulcanization mold to be cleaned. Thus, by comparison to a circular shape, the result is a much improved sound isolation or sound absorption due to the more diffuse reflections and interferences of the sound waves within the polygon. With this kind of design we have a much improved resonance behavior in the sense of a reduction in resonance.
In yet another favorable design, the device features one central, or possibly several dependent, control devices and appurtenant sensor devices for all movement axes. Thus, the overall sequence of the cleaning process or parts thereof can be automated in a simple manner.
In yet another favorable design, the transport device is designed as a floor-mounted and free-moving cleaning cart, so that cleaning and access through normal transport and access routes is possible, without complicated rail or traverse guides.